The effect of SiC amount on microstructure and wear properties in SiC-reinforced Mo5SiB2

Abstract

This study aimed to investigate how silicon carbide (SiC) reinforcement affected the microstructure and wear properties of Mo5SiB2-based alloy fabricated by powder metallurgy. The main reasons for using SiC in this study are that it is affordable and improves the wear resistance of the Mo5SiB2-based alloy. SiC at 2 %, 4 %, and 6 % by volume was added to Mo5SiB2-based alloy. After cold pressing and sintering, the samples' microstructure, density, hardness, and wear properties were analyzed in detail. Scanning electron microscope (SEM) images indicated that a porous and skeletal structure formed as a microstructure. This structure became more pronounced with an increased SiC rate. X-ray diffraction (XRD) results showed that Mo5SiB2 (T2 phase), Mo3Si (A15 phase), α-Mo, SiO2, and SiC phases formed in the microstructure. With increasing SiC rate, the peaks of binary and ternary phases increased. The experimental densities dropped upon the reinforcement of SiC. The hardness of the samples reached the maximum value (1639HV2) in the Mo-Si-B alloy at 6 % SiC rate. The results of the pin-on-disk wear tests run to assess the wear performance of the samples indicated that the best wear performance was achieved in the 6 % SiC-reinforced sample with a coefficient of friction (COF) of 0.49 and a wear rate of 0.43 × 10−5 mm3 (N.m)−1.